package chapter2;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

/**
 * Basic IO example with CTR using AES
 */
public class SimpleIOExample {
    public static void main(
            String[] args)
            throws Exception {
        byte[] input = new byte[]{
                0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
                0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
                0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06};
        byte[] keyBytes = new byte[]{
                0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
                0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
                0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17};
        byte[] ivBytes = new byte[]{
                0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x02, 0x03,
                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01};

        SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
        IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
        Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding", "BC");


        System.out.println("input : " + Utils.toHex(input));

        // encryption pass

        cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec);

        ByteArrayInputStream bIn = new ByteArrayInputStream(input);
        CipherInputStream cIn = new CipherInputStream(bIn, cipher);
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        int ch;
        while ((ch = cIn.read()) >= 0) {
            bOut.write(ch);
        }

        byte[] cipherText = bOut.toByteArray();

        System.out.println("cipher: " + Utils.toHex(cipherText));

        // decryption pass

        cipher.init(Cipher.DECRYPT_MODE, key, ivSpec);

        bOut = new ByteArrayOutputStream();

        CipherOutputStream cOut = new CipherOutputStream(bOut, cipher);

        cOut.write(cipherText);

        cOut.close();

        System.out.println("plain : " + Utils.toHex(bOut.toByteArray()));
    }
}
